Arc extinguishing switch structure



June 29, 1965 KARL-LUDWIG GEssNER 3,1925348 ARC EXTINGUISHING SWITCH STRUCTURE Filed Feb. l5, 1962 2 Sheets-Sheet l .[m/eman' KcufL- Ludwig G essner June 29, 1965 KARL-LUDWIG GEssNER 3,192,343

ARC EXTINGUISHING SWITCH STRUCTURE 2 Sheets-Sheet 2 Filed Feb. 15, 1962 [nre/vfat' Ko. L- Luvo Gessnev Gimme-,g v

United States Patent O ce 3,192,348 ARC EXTINGUISHENG SWHCH STRUCTURE Kari-LudwigVGessner, Darmstadt, Germany, assigner to Lieentia Patent-Verwaltungs-Gmb.H., Frankfurt am Main, Germany Fiied Feb. 15, 1962, Ser. No. 173,400 Claims priority, application Germany, Feb. 20, 1961,

38,244 12 Claims. (Cl. Zitti-144) The4 present invention relates generally to the switch art, and, more particularly, to an arc extinguishing assembly for switchgear having contacts or other arc generating elements and using electrically conductive arc extinguishing baliles which are aligned at right angles to the arc.

n Arc extinguishing assemblies of this type are particularly used in alternating current types lof low tension or low voltage switches, for example, protective and power relays. 'The arc which is formed in the switch upon opening the contacts is usually forced, by a magnetic effect, against the edges of the arc extinguishing bafes and this arc is eventually split up into short partial arcs disposed between the baffles. At the natural zero point of the alternating current, the a-rc is extinguished.

The instantaneous stabilization -of the arc path, which occurs during this extinction, increases proportionately with the number of partial arcs, and thus with the number of extinguishing batiies. The cooling and deionization of the arc gases which are also effected by the baffles, enhance restabilization of the arc path after the switch is opened. Such arc extinguishing assemblies are theoretically more effective if more arc extinguishing baies are used and if a smaller distance is provided between the individual bales.

However, in arc extinguishing baffle assemblies, there is difficulty in forcing the arc quickly and reliably into the arc extinguishing baffle section. The use of more numerous bafes and narrower distances between the bafties, renders it more diicult to force the arc between the baffles and causes it to form bases on the individual baffles. Often, the arc is maintained in front of the `arc extinguishing baffle section for a relatively long period of time so that reliable opening of the switch is not always assured. Furthermore, opening ofthe switch, or switching it off, in such an event, causes a marked burning of the edges of the baffles and thereby renders the arc extinguishing assembly prematurely unusable. In the conventional type of rectangular arc extinguishing baiiie, the arc must extend or bend so far about the edge of the baie on which it is to form a base, that it is lengthened and this lengthening provides the necessary voltage for the base formation. When closely spaced baffles are used, this is not possibleunless there is a very vigorous magnetic effect upon the arc. In baffles which are too closely spaced, the arc will not go into the arc extinguishing baffle section at all. Y

Attempts have been made in the past to eliminate this drawback by providing the bales with a wedge-shaped slot or recess. In such a device, the voltage which is necessary for the base formation of the arc is generated by narrowing the cross section ofthe arc which extends into the slot. ,Due to the narrowing of the cross section and intense cooling due to the baffles, by the time the arc has arrived at the end of the slot, i.e., at a point beyond the narrowed cross section, there is a voltagedrop which is suflicient for base formation. g However, in these slotted bafes re-ignitions may occur in the wedgeshaped slots. The space at the beginning of the slot over which the arc has just travelled is still so well ionized,

3,192,348 Patented June 29, 1965 that the voltage increase of the arc which arrives at the end of the slot is sufficient to cause re-ignition at the broader entrance of the slot. The effect of this is that the :arc which has already moved into the baies is extinguished and the arc voltage breaks down. In this manner, the process of the arc entering or moving into the baliles may be repeated several times. This causes the opening or switching off of the switch to be delayed, and burning of the edges of the bales is increased.

With these defects of the prior art in mind, it isa main object of the present invention to eliminate the abovemention-ed drawbacks of the prior art which, under some circumstances, will considerably impair the effectiveness of an arc extinguishing device. f

Another object of the invention is to provide arc extinguishing baies which are adapted to readily cause the arc to form partial arcs and to travel between the baffles, even when a large number of baffles are used and when they are closely spaced.

A further obj-ect ofthe present invention is to provide an arc extinguishing device which is superior to known devices due to the combination of good arc entry properties, as well as an inhibition of re-ignition, especially in switchgear which does not have any additional extinguishing of the arc by blowout coils -or other types of auxiliary means.

These objects and others ancillary thereto are accomplished according to preferred embodiments of the invention wherein at least some of the arc extinguishing battles are perforated at their ends nearer the arc generating portion of the device in such a manner that the aperture or opening area provided by the perforations and available to the arc for passage decreases in the direction of motion of the arc.

The present invention is based on the fact that the arc forms an anode base and a cathode base on a baiie only, if, at the section between the bases to be formed, there is a voltage Which at least corresponds to the sum Iof the anode drop and the cathode drop.

The sieve-like perforations of the baffles also eliminate the drawbacks caused by a recycling or re-igniti-on of the arc. When the arc reaches the batlies it burns in parallel branches through several perforations. The transition of the condition of the arc before reaching the baffles into the condition stated above proceeds without diculties. The perforations are so arranged that with further movement `of the arc into the arc extinguishing baie section, the number or cross section of the perforations available to the arc for passage decreases. Due to the cooling and a decrease in cross section, the voltage rises until finally the voltage drop of the arc column along the narrow point attains the sum of the cathode drop and lthe anode drop, and the arc forms bases or base points on the batiles.

However, at the same time, the perforations which have already been passed by the arc are very well deionized by the metal grid in a substantially better manner than that which is accomplished with the aforementioned slotted baiiies, so that reignition or" the arc in the region already passed by the arc will no longer occur. In the limiting case, this metal grid may comprise a member with but a single opening.

Additional objects and advantages =of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE la is an elevational view of a rectangular arc extinguishing baffle of the conventional type for an arc extinguishing chamber.

FIGURE lb is a diagram showing a graph indicating various characteristics of such a conventional baffle.

FIGURE 2a is an elevational view of an arc extinguishing baille of the typeY which is perforated in accordance with the present invention.

FIGURE 2b is a diagram showing a graph indicating the characteristics of the baille of FIGURE 2a similar to those indicated for FIGURE lb. l

FIGURE 3 is an elevational View of a first embodiment of a baille constructed in accordance with the present invention.

FIGURE 4 is an elevational view of a second embodiment of the present invention.

FIGURE 5 is an elevational view of a third embodiment of the invention.

FIGURE 6 is an elevational view of a fourth embodiment of the invention.

FIGURE 7 is an elevational view of a fth embodiment of the invention.

FIGURE S is a diagrammatic sectional view illustrating an arc extinguishing baille assembly as it would be used in switch-gear.

With more particular reference to the drawings, and especially to FIGURES lz,A lb, and 2a, 2b, it should be noted that in the diagrams of FIGURES lb and 2b a constant arc current is assumed. The course S of the arc is indicated, as well as the are voltage Va and the arc power P, all of which are plotted against` time t.

In FIGURE lb, the arc is magnetically forced into the arc extinguishing assembly and reaches the edges of the bailles at instant t1. The are remains in this position until instant t2. The arc path time-line S results from the time t when the arc is burning and extends horizontally. During this time, the arc voltage Va rises continuously, since the arc increases in length by travelling into the spaces between individual baflles and because it transfers energy to the balles.v Furthermore, the power P rises to the same extent as the voltage Va. The area Alzis the energy which is converted from the arc during the time it remains in front of the baffles. This energy is responsible for they marked burning of the front edges of the bailles.

At instant t2, base points have been formed on the ballles anda partial arc has travelled into the baille assembly. In case Vdividing or splitting up of the arc does not occur at all, which may be the case with this type of baille, the time period t1 to t2 will last until the zero point of the current, thereby increasing the area Am, i.e., the energy which is transmitted to the bailles, and also there-` by increasing the amount of burning away of these bailles.l

With more particular reference to FIGUREy 2b, the` time t1 to t2, during which the arc is present at the front edges of the bailles, is extremely short. With the use of these sieve-like perforated battles of the type indicated in FIGURE 2a, the are no longer has to increase in length by bending about front edges of the bailles, and therefore the voltage V,L and the conversion of power P are stilll low. Therefore, the energy conversion in front of the baille assembly which is represented by area Alz will remain very small. A burning Aof the edges of the battles will therefore no longer occur.`

From instant t2 to t3 the arc will burn through the perforations and continuously move into the apertures of smaller cross section. Because ofthe decrease of the cross section of the arc, the voltage and power will continuously rise until, at instant t3, the arc will form base points on the baflles and will travel along the baiiles.

The energy conversion during the movement of the arc over the series of perforations is represented by area Aza. However, this latter energy conversion does not cause damaging of the battles during the conversion because the are keeps moving and constantly sweeps over new points along the baflles.

FIGURES 3 through 7 illustrate a few of the many possible embodiments of the ballles which may be constructed in accordance with the present invention. These batlles which may be constructed, for example, of iron,

are provided on their respective end 2 which faces the incoming arc, with sieve-like perforations which provide openings or apertures 3 in Which the arc may burn in parallel branches. The openings 3 are distributed in the ballles in such a manner that there is a stepwise decreasing opening cross section available for the arc, and the number and area of the apertures are designed accordingly. In this manner, this aforementioned stepwise decrease in the available cross section of the openings for the arc is in the direction of travel indicated by arrow A. In the extreme or limit case, the perforations may comprise a single opening in the form of a triangle as illustrated in FIGURE 7 and having lugs 9 projecting into the opening.

The remaining portion of each baille which is disposed between or about the openings4 provides good deionization of the ionized gas which remains behind the arc proper so that reignitions in the area which the arc has already passed no longer occur. With the generally used, relatively thin, batlies, it is expedient to provide the cross sectional area of the openings as being approximately equal to the area of the baille material remaining between or about the openings.

FIGURE 8 is a diagrammatic sectional viewof an embodiment wherein an are extinguishing baille assembly is` provided. For purposes of clarity, only a few of these baflles are shown. The baflles 4 are provided with the type of perforations described above in accordance with the present invention. The openings are indicated by numeral 3, and the ends 5 of all of the batlles, which ends are remote from the arc, are bent at an angle of with respect to the body of the ballles. The arms 6 between the two parallel legs of the batlles are provided With outlet openings 7. This is a particularly favorable embodiment of the baflles. Due to the perforations, a reliable and rapid entry of the arc into the extinguishing assembly is provided. As soon as the arc reaches the short legs 5 of the batlles, its rapid travel is slowed due to an electro-dynamic counter extinguishing effect, there-V by preventing the arc from flashing out of the extinguishing assembly. The openings 7 and the narrow slots 8 between the end of the bailles provide for rapid restabilization of the chamber space and prevent reignition of the arc after its natural extinction at the zero point of the current.

It will be understood that the above description of the present invention is susceptible to various modifications,l changes, and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

What is claimed is:

1. An are extinguishing device for electric switchgear having con-tracts or other arc generating elements, comprising a plurality of electrically conducting arc extinguishing batlles `arranged at right angles to arcs which are generated, at least some of the ends of the ballles facing the place where the are is generated bearing perforated by -at least one opening, with an opening area provided thereby being available to the arc for passage there-A along, and decreasing in the direct-ion of mot-ion of the lac.

k2. A device as defined in claim 1 wherein the number of openings decrease in the direction of motion of the are.

y3. A device as defined in claim. 1 wherein several series of open-ings are arranged in the direction of mot-ion of the arc, each series of openings having at least one perfo` ration ywith an open-ing cross section which decreases in the direction of motion.

4. A device as defined in claim 3 wherein the openings :are triangular in shape and the vert-ex of the tri-v angle points in the direction of motion of t-he arc.

'5. A device as defined in claim 1 wherein a single opening is provided in each baille.

areas-as 6. A ldevice -as defined in claim wherein the single yopening is triangular and lugs project into the triangular opening.

7. A device as deiined in claim 1 wherein the opening area and the solid .area of the baffle material remaining .around the open-ing area are approximately equal.

rfi. A device as deiined in claim 1 wherein at least :some of the batie ends remote from the point where .the arc is gener-ated, `are bent to face the direction of the incoming arc with the -facing end `being perforated in at least lone row.

9. In an .arc extinguish-ing device for elect-ric switchgear which generates arcs, the .device being of the type having electrically conducting -arc extinguishing baffles .arranged at right angles to the arc which is generated, the improvement tha-t: at least some of the ends of the baiiies nearer the location of arc genera-tion have rnultiple perforations arranged in zones so that a plurality of aperture areas are dened Iby the perorations and available to the are for passage, and the aperture area in each successive zone in the direc-tion in which the arc travels decreases wit-h respect to the aperture area in the preceding zone.

`10. In an arc extiguishing device for electric switchgear which generates arcs, the device being of the type having electrically conducting arc extinguishing bailies arranged at right angles to the arc Which is generated, the improvement that: the baffles are formed for an easy entering of the arc Iinto the baffle combined with the increase rof the tension of the .are to let the `are have arc burning bases on the baies whereby the arc is :inhibited for re-ignition in the portion of the baille where the are enters the baie because the form of the baille gives a deionizat-ion of the entering way yof the arc intro the baffle.

lill. An arc extinguishing device for electric switchgear having are generating elements, comprising a plurality of electrically conducting arc extinguishing baffles arranged at right angles to arcs which will be generated, `at least one opening surrounded by the solid material of the baie and formed in the ends of a-t least some of the baiiles thereby to deline perfo-rate portions -on at least some of the baiiies, said ends facing the place Where arcs lwill be generated, said perforate portions each having an opening area available to the arc for passage therealong, said area decreasing in the 'direction of motion lof the arc.

12. A device as defined in claim 1:1 wherein said Vopening area continuously decreases -in the direction of motion `of the arc.

References Cited by the Examiner UNITED STATES PATENTS 1,868,442 7/32' Corbett .ZOO-144 r140,8 60 12/3 8 Jennings 20D-144 2,616,006 10/52 Frink 200-144 `2,707,218 4/ 5 5 Cellerini ZOO-144 2,7 24,7 5 4 11/55 Timmerman ZOO-144 y2,769,066 `10/ 5 6 Cellerini 200-147 3,126,464 3/ 64 Stettnerk 20G-144 FOREIGN PATENTS 1,089,03 8 9/60 Germany.

BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

NITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,192,348 June 29, 1965 Karl-Ludwig Gessner It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 57, for "bearing" read being Signed and sealed this 28th day of December 1965.

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer AEDWARD J. BRENNER Commissioner of Patents 

1. AN ARC EXTINGUISHING DEVICE FOR ELECTRICAL SWITCHGEAR HAVING CONTACTS OR OTHER ARC GENERATING ELEMENTS, COMPRISING A PLURALITY OF ELECTRICALLY CONDUCTING ARC EXTINGUISHING BAFFLES ARRANGED AT RIGHT ANGLES TO ARCS WHICH ARE GENERATED, AT LEAST SOME OF THE ENDS OF THE BAFFLES FACING THE PLACE WHERE THE ARC IS GENERATED BEARING PERFORATED BY AT LEAST ONE OPENING WITH AN OPENING AREA PROVIDED THEREBY BEING AVAILABLE TO THE ARC FOR PASSAGE THEREALONG, AND DECREASING IN THE DIRECTION OF MOTION OF THE ARC. 